Focusing device for roll-film cameras



Nov. 9, 1943. B. A. PARR FOCUSSING DEVICES FOR ROLL-FILM CAMERAS Filed NOV. 17, 1939 4 Sheets-Sheet 2 INVENTO R BERNARD Aemuz FARR BY ATTORNEYS Nov. 9; 1913. a. A. FARR FOCUSSING DEVICES FOR ROLL-FILM CAMERAS Filed Nov. 17, 1939 4 Sheets-Sheet 3 I NV EN TOR BERNARD Aamux FARR BY fi/ ATTORNEYS camera of Fig. 1 with Patented Nov. 9, 1943 FOCUSING DEVICE FOR ROLL-FILM CAMERAS Bernard Arthur Parr, East Sheen,

London. England, assignor to The Houghton-Butcher Manui'acturing Company Limited,

a British company Application November 17, 1939, Serial No.

land,

London, Eng- In Great Britain November 21, 1938 10 Claims. (Cl. 95-45) The present invention relates to roll-film photographic cameras, and an object of this invention is to provide an improved focusing device which may if desired be combined with range finding means.

Broadly the invention involves the shifting of the focal plane of the camera, 1. e., the plane of the film towards or away from the lens rather than shifting the lens relatively to the camera body.

According to the present invention focusing is effected in a roll-film camera by shifting the plane of the portion of the film to be exposed relatively to the camera body, the lens being, when in the position for use, immovably located with respect to the body, the said portion of the,

film being located by a member or members controllably movable in the direction of the optical axis.

Any suitable means may be used for controlling the film locating member, these means advantageously being mounted on the camera body. While the invention is not limited to cameras embodying a range finder it confers additional advantages when applied to such cameras since when the focusing control means are mounted wholly on or within the camera body they may readily be coupled to a range finder mounted thereon whereas in cameras in which the lens system is moved relatively to the camera body complicated linkage systems are required to couple the lens moving mechanism to a range finder mounted on the camera body.

Three constructional arrangements in accordance with this invention are illustrated by way of example only in the accompanying drawings.

In the drawings Fig. 1 is a front elevational view of a camera in accordance with the invention with parts cut away to show the focusing mechanism;

Fig. 2 is a side elevation showing the bottom of the camera of Fig. 1 with the cover removed to show the range finder;

Fig. 3 is a sectional view on the line III-III of Fig. 1;

Fig. 4 is a side elevation of the top of the parts of the cover removed;

Figs. 5 and 6 are diagrammatic sectional views in side elevation of alternative arrangements of focusing mechanism in accordance with this invention.

Referring to Figs. 1 to 4: a camera comprises abody In provided with a back cover II and having in the front a hinged baseboard l2 which supports the lens panel, shutter, etc., I3. The lens panel is preferably of the self erecting type. When the lens panel is erected the lens is held immovably with respect to the camera body, ho focusing movement of the lens being provided.

Since this invention is not concerned with the erecting linkage or other means this will not be described, it being understood that any suitably rigid arrangement may be used.

The camera body I0 is provided in the front with a recess formed by inwardly directed flanges H with inturned edges I5 which lie parallel to and a short distance in front of the focal plane. A camera bellows l6 secured to the inturned edges l5 encloses the space between said edges and the lens panel. When the camera is closed the lens panel and bellows lie in the recess in the camera body and are covered by the hinged baseboard i2 which is slightly dished to give additional space. Optionally this may be arranged to accommodate filters or supplementary lenses in position in front of the lens of the camera.

At the ends of the camera are provided spool chambers i1 and i 8 which contain the max posed" and "exposed spools i9 and 20 respectively. The film 2| passes from the spool l9 to the spool 20 over rollers 22 and 23 at the ends of the focal plane, beingmaintained in contact with the rollers by a pressure plate 24. The pressure plate 24 is urged forwardly by long springs 25 arranged between it and the back of the camera ll. Means, not shown, are provided for locating the pressure plate in the camera to prevent its movement with the film 2i when it is wound on. The travel of the film is effected by a knob 26 which has a spindle engaging the spool 20. The spool I9 is held in position by a spring loaded spindle having a knob 21 at one end. In the arrangement shown the film has a backing strip and is wound from the "unexposed to the "exposed spool but it is obvious that the arrangement may be modified for use with cassette loading.

The rollers 22,23 which engage the film at the ends of the focal plane are rotatably mounted on lugs 28 extending upwardly and downwardly from flanged parts 29 of an apertured plate 30. The edges of the aperture in the plate 30 form a mask for the picture space on the film.

When ready for exposure the film 2| is held between the rollers 22 and 23 and the pressure plate 24. Focusing adjustment is effected by moving these parts bodily in the direction of the optical axis, thus shifting the focal plane relatively to the camera body. In the arrangement shown in Figs. 1 to 4 the movement of the focal plane is effected by. rotation of a focusing knob 3| mounted on a shaft 32 which extends across the camera'from top to bottom. The shaft 32 has eccentrically arranged pins 33 a short distance from each end which engage slots 34 in the lugs 23 carried by the apertured plate 33. When the shaft 32 is rotated clockwise from the position shown (Fig. 3) the apertured plate 33 is moved rearwardly relatively to the camera body so that the distance between the lens and the film is increased.

The shaft 32 carries a pinion 35 which engages a rack 33 on a member 31 which extends within a cover along the bottom of the. camera as seen in Fig. 1. A similar rack 33 at the other end of the member 31 engages a pinion 33 mounted on a shaft 43 similar to the shaft 32 and which is arranged at the opposite end of the focal plane. The shaft 43 carries eccentrically disposed pins 4|, the eccentricity being the same as that of the pins 33 on the shaft 32. The pins 4| engage slots 34a in lugs 23 at the end of the apertured plate 33.

It will be seen that the apertured plate 33 is located adjacent each of its corners, the positions of which are controlled by the pins 33 and 4| carried on the shafts 32 and 43 respectively. The shafts 32 and 43 are moreover coupled together by the rack member 31 so that they must move simultaneously thus preventing any displacement direction of the arrow A along the dotted line. One part of the field is seen through the upper (unsilvered) part of the mirror 33, which is secured by springs 3| bolted at.32 to a block 33, the position of which is adjustable relatively to a plate 34 mounted on the camera body. The correct levelling of the mirror 63 is effected by adjustment of three screws 35.

The other half of the fleld is seen in the lower silvered part of the mirror 33 being reflected from a movable mirror 33 coupled to the focusing knob 3|. The mirror 33 is carried on a bracket 31 which is adjustably mounted on an arm 13 pivoted at 1| to the camera body, levelling adjustment of the bracket 31 being effected by three screws 33 and a locking screw 33. The end of the arm 13 remote from the pivot 1| has, on its under surface, two bushes 13 which slide over the base plate 12 as the range-finder is adjusted. A leaf spring 14 is arranged to press the bushes 13 against the base plate. The arm 13 also has a plate 15 bolted to its upper surface at its free end by two bolts 13, 11, the latter being adjustable along a slot 13 in the plate 15. The plate 15 carof the apertured plate 33 from a plane perpendicular to the optical axis of the lens. To ensure that this condition is maintained great accuracy in manufacture and adjustment is essential and backlash in the mechanism must be eliminated. To ensure that the racks 33 and 33 on the member 31 closely engage their respective pinions 35 and 39, means are provided for adjusting the position of the member 31 relatively to the shafts 32 and 43. At each of its ends the member 31 has a slot 42 which is engaged by a headed bolt 43 the shank of which is a close fit in the slot 42. The bolts 43 are secured to sector plates 44 which are pivotally connected to the camera body I3 at points 45 which in the mid position of adjustment as shown lie outside the axes of the bolts 43. Each sector plate 44 has an arcuate slot 43 which is engaged by a bolt 41 for locking the plate to the camera body. By moving the sector plates 44 relatively to the camera body the racks 33 and 33 can be moved towards the pinions 35 and 33 to compensate for any wear which may occur.

The limits of longitudinal travel of the rack member 31 are controlled by engagement of the head of a bolt 43 mounted thereon with the ends .of a slot 49 in a plate 53 adjustably secured to the camera body by two bolts 5| which pass through an elongated slot 52 in the plate 53. The plate 53 is secured in the position in which the camera is focused at infinity when the bolt 43 is at the upper end of the slot 43.

A great advantage of having the partswhlch are required to move for focusing adjustment housed within the camera body is that the focusing control can readily be coupled to these parts whereas when the focusing adjustment is by relative movement between the lens panel and the camera body a complicated linkage which also has to allow of folding of the camera is necessary.

In the camera illustrated in Figs. 1 to 4 a shortbase range-finder of the split image type is coupled to the focusing knob 3|. The arrangement is shown in Fig. 2. The observer looks in the ries a pin 13 which is pressed by a spring 33 into contact with cam surface 33 of a crank arm 3| pivoted at 32 to the camera body. Adjustably secured to the other arm of the crank arm 3| is a lever 34 having a slot 33 engaged by a screw 35 for clamping the lever 34 and crank arm 3| together. The end of the lever 34 remote from the pivot 32 is maintained in contact with a rangefinder coupling 31 by a spring 33. The coupling pin 31 is mounted on one of the lugs 23 on the apertured plate 33, as shown in Fig. 3.

As the apertured plate 33 is moved in the direction of the optical axis for focusing, the coupling pin 31 moves in a slot 33 in the camera body I3. This causes pivotal movement of the lever 34 and crank arm 3| about the pivot 32 and hence relative movement between the cam surface 33 and the pin 13. The pin 13, being urged by the spring 33 against the cam surface 33, causes movement of the arm 13 carrying the mirror 33 about the pivot H. The cam surface 33 is so designed as to provide the correct relation between the movement of the focusing knob 3| and the angular movement of the range-finder mirror 33.

Fig. 5 shows an alternative construction in which the camera body I33 has an inturned flange I3I with edges I32 to form a recess in the front of the camera body in which recess the camera bellows I03, lens panel and associated parts (not shown) are housed when the camera is closed. The back of the camera is closed by a back plate I34 which forms the reaction surface for the springs I35 of a pressure plate I33. The film I31 passes from an upper spool I33 in the upper spool chamber I33 over rollers IIII, III against which it is pressed by the pressure plate I33 to the lower spool H2 in the lower spool chamber H3. The rollers II3, III are in the form of sleeves which are freely rotatable on spindles H4, H5 secured at one end in an eccentric position to pinions I I3, I I1 which are mounted for rotation about axes H8, H9 respectively. The pinions H3 and' I I1 ar coupled together to move simultaneously and by equal amounts by a rack member I23 which is moved lengthwise relatively to the camera body to cause rotation of the pinions and hence movement of the axes of the film rollers II3, III having a component in the direction of the optical axis thus moving the focal plane relatively to the camera body and lens panel which latter is. when erected, located immovably with respect to the camera. body.

Fla. 6 shows a second alternative construction in which the camera body I50 has an intumed flange I5! and has secured to its front part the rigid lens mounting I52, which may be detached by unscrewing a bolt I53. .Clamped between the lens mounting I52 and the body of the camera is a ring I54 which is internally screw threaded for engagement with an external screw thread on an annular member I55. The member I55 engages at its inner end an apertured plate I56 against which the film I5I is pressed by a pressure plate I58 having springs I59 between it and the back of the camera I50. The focusing control arm I5I is joined to a ring I52 and is rotatable relatively to the camera body I50. The ring I52 is coupled to the annular member I55 by a pin I53 on the latter which engages a slot I54 in the ring I52 so that rotational movement can be transmitted from the ring I52 to the member I55 while allowing the latter to move in the direction of the optical axis under the action of the screw thread.

When the focusing control arm I5l is moved, rotation of the ring I52 causes rotation of the annular member I55 which moves in the direction of the optical axis, moving with it the apertured plate I 56, film I51 and pressure plate I58. The apertured plate is restrained against rotation by flanges I55 which engage noncircuiar parts of the flange I5I on the camera body. By this means the focal plane is moved relatively to the camera body.

What I claim is:

1. A roll-film camera comprising in combina tion a lens immovably located with respect to the camera body when in a position for use, a spring loaded pressure plate, an apertured plate disposed between the pressure plate and the lens, and means on said said apertured plate adapted to engage only that portion of the film extending between the film rolls, the film when in position being held between the pressure plate and said means and means for controllably moving the apertured plate relatively to the camera body for focusing adjustment.

2. A roll-film camera comprising in combination a lens immovably located with respect to the camera body when in a position for use, a spring loaded pressure plate, an apertured plate disposed between the pressure plate and the lens, and carrying rollers on said apertured plate adapted to engage only that portion of the film extending between the film rolls, the film when in position, being clamped between the pressure plate and said rollers and means for controllably moving the apertured plate relatively to the camera body for focusing adjustment.

3. A roll-fihn camera comprising in combination a lens immovably located with respect to the camera body when in a position for use, a spring loaded pressure plate, an apertured plate disposed between the pressure plate and the lens and means on said apertured plate adapted to engage only that portion of the film extending between the film rools, the film when in position being held between the pressure plate and said means and means for controllably moving the apertured plate relatively to the camera body for focusing adjustment comprising a slotted lug on the apertured plate, an external focusing control and a pin eccentrically mounted on the shaft of said control and engaging said slotted 1118.

4. A roll-film camera comprising in combination a'lens immovably located with respect to the camera body when in a position for use, a springloaded pressure plate, an apertured plate disposed between the pressure plate and the lens, and carrying rollers on said apertured plate adapted to engage only that portion of the film extending between the film rolls, the film which in position for exposure is clamped between the pressure plate and the rollers and means for controllabl moving the apertured plate relatively to the camera body for focusing adjustment comprising a plurality of slotted lugs disposed atin the direction of the optical axis and relatively to the camera body for focusing adjustment.

6. A roll-film camera comprising in combination a lens immovably located with respect to the camera body when in a position for use, a springloaded pressure plate, a roller adjacent each end of the portion of film to be exposed and against which the film is pressed by the pressure plate, each of said rollers consisting of a sleeve rotatably carried on a spindle mounted on eccentrics which are rotated relatively to the camera body for focusing adjustment.

7. In a roll film camera, a lens, a mounting portion of the film is positioned for exposure, a

mounting for said film guide means whereby perpendicularity thereof to the axis of the lens is maintained, and focusing control means operable at will to impart to said film guide means bodily movement in relation to said spool holders away from and towards the lens.

8. In a roll film camera, a lens, a mounting for said lens whereby it is positioned immovably for use, parallel spaced holders for film spools, movable film guide means located between said holders for guiding only a portion of film which extends between spools in said holders, said film bearing upon said film guide means at that side of the latter remote from the lens whereby such portion of the film is positioned for exposure, a mounting for said film guide means whereby perpendicularity thereof to the axislof thelens is maintained, range finding means, and focusing control means coupled operatively with said range finding means and operable at will to impart to said film guide means bodily movement in relation to said spool holders away from and towards the lens.

9. In a roll film camera, a lens, a mounting for illm guide means at that side of the latter remote from the lens whereby such portion of the film is positioned for exposure, a mounting for said film guide means whereby perpendicularity thereof to the axis oi the lens is maintained, and focusing control means whereby bodily movement in relation to the spool holders away from and towards the lens may be imparted at will to the film guide means.

10. A camera comprising in combination, a camera body having a screw thread, film rolls within said body for supporting a film, a lens immovably located with respect to the camera body when in position for use, an apertured plate disposed on the lens side or the film so as to bear only on that portion of the film extending between the fllm rolls in position for exposure, a spring-loaded pressure plate disposed to hold the film against said apertured plate, an annular member in engagement with said apertured plate to retain the latter in contact with the film and having a screw-thread engaging said screwthread on the camera body, and means for rotating said annular member relatively to the camera body to thereby move said apertured plate for focusing adjustment.

BERNARD ARTHUR FARR. 

